Article: Carbidopa

Carbidopa (MK-486) is a drug given to people with Parkinson's disease in order to inhibit peripheral metabolism of levodopa.

Carbidopa inhibits aromatic-L-amino-acid decarboxylase (DDC), an enzyme important in the biosynthesis of L-tryptamine to 5-HT and in the biosynthesis of L-DOPA to Dopamine (DA). Along with carbidopa, other DDC inhibitors are benserazide (Ro-4-4602), difluromethyldopa, and a-methyldopa.

Used in tandem with levodopa (l-dopa, a dopamine precursor converted in the body to dopamine), it increases the plasma half-life of levodopa from 50 minutes to 1 1/2 hours. The combination carries the brand name Sinemet.